"At the end of the day we are both professionals and once we step on the court we want to win the match regardless who is across the net," Djokovic said.

"Of course it is a bit different feeling when your opponent is a long-time friend and obviously I wanted to laugh at his jokes but on the other hand I didn't want to lose any concentration and it was very important to stay focused until the end."

The Serb will now face Stanislas Wawrinka
after the Swiss No.8 seed overcame Tommy Robredo in the evening match on Rod Laver Arena. Wawrinka won 6-3 7-6(3) 7-6(5) to set up a repeat of last year's meeting with Djokovic, an epic last-16 encounter that finished at 1.41am local time.

Meanwhile, Ferrer came from a set down to see off Florian Mayer 6-7 7-5 6-2 6-1 and book his quarter-final spot.

Ferrer was broken in the first game and soon found himself 3-1 down in the first set, before losing out on a tie breaker. However, after edging a tight second set, Ferrer dropped only three more games on his way to completing victory.

He will now face Tomas Berdych in the quarter-final, who defeated Kevin Anderson 6-2 6-2 6-3 in their fourth round match.